DC-DC power conversion units designed with synchronous rectifier output field effect transistors (FET)s or other power switch technology and connected with paralleled outputs utilizing voltage droop for current sharing may have reverse current issues during start-up if isolating circuitry (e.g., OR-ing diodes or FETs) is not used on each of the outputs to prevent sinking current into the power conversion units. Output voltage droop is a feature by which the output voltage regulation set-point is reduced as a function of the output current. For example, the output voltage set-point at no load may be 12.0 Vdc and be reduced to 11.5 Vdc at full load. Unless the power conversion units start with perfect synchronization, one or more units may sink current when powered up using a normal soft start turn-on sequence, since the first unit to start will provide a pre-bias condition to those units which turn on later. The sinking or reverse current can be as large as the over-current protection level of one or more of the sourcing units and may cause damage to those units that are sinking current.